Tuesday, February 17, 2015

New paper demonstrates East Antarctica was ~3.5-4°C warmer than the present during the last interglacial

A new paper in Climate of the Past Discussions finds from high-resolution ice core data from East Antarctica that temperatures were 3.5-4°C warmer during the last interglacial (~130,000 years ago) than during the present interglacial (the past ~18,000 years).

The IPCC claims warming of over 2°C (an arbitrary figure 'plucked out of thin air') will lead to irreversible and catastrophic "tipping points" or positive feedbacks from which Gaia cannot recover. However, the ice core data from prior interglacials demonstrates this is not the case, and that both Greenland and Antarctica recovered from warming of 8°C and 4°C higher (respectively) during the last interglacial and relative to 1950, and both ice sheets are much larger today than during the past interglacial.

In addition, the ice core data demonstrates that such dramatic changes at the poles occur by entirely natural means and thus, there is no evidence that the (less) dramatic climate changes seen during the current interglacial are unnatural, unusual, or unprecedented.

Second graph from top shows reconstructed temperatures at 2 ice core sites in East Antarctica. Horizontal axis is thousands of years before 1950. Note surface temperatures have warmed about 0.5C since 1950.

F. Parrenin1,2, S. Fujita3,4, A. Abe-Ouchi5,6, K. Kawamura3,4, V. Masson-Delmotte7, H. Motoyama3,4, F. Saito5, M. Severi8, B. Stenni9, R. Uemura10, and E. Wolff111CNRS, LGGE, 38041 Grenoble, France2Univ. Grenoble Alpes, LGGE, 38041 Grenoble, France3National Institute of Polar Research, Research Organization of Information and Systems, Tokyo, Japan4Department of Polar Science, The Graduate University for Advanced Studies (SOKENDAI), Tokyo, Japan5Japan Agency for Marine–Earth Science and Technology, Yokohama, Japan6Atmosphere and Ocean Research Institute (AORI), University of Tokyo, Chiba, Japan7Laboratoire des Sciences du Climat et de l'Environnement, Institut Pierre Simon Laplace, UMR CEA-CNRS-UVSQ 8212, Gif-sur-Yvette, France8Department of Chemistry, University of Florence, Florence, Italy9Department of Geosciences, University of Trieste, Trieste, Italy10Department Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus, Okinawa, Japan11Department of Earth Sciences, University of Cambridge, UKAbstract. Documenting past changes in the East Antarctic surface mass balance is important to improve ice core chronologies and to constrain the ice sheet contribution to global mean sea level. Here we reconstruct the past changes in the ratio of surface mass balance (SMB ratio) between the EPICA Dome C (EDC) and Dome Fuji (DF) East Antarctica ice core sites, based on a precise volcanic synchronisation of the two ice cores and on corrections for the vertical thinning of layers. During the past 216 000 years, this SMB ratio, denoted SMBEDC/SMBDF, varied between 0.7 and 1.1, decreasing during cold periods and increasing during warm periods. While past climatic changes have been depicted as homogeneous along the East Antarctic Plateau, our results reveal larger amplitudes of changes in SMB at EDC compared to DF, consistent with previous results showing larger amplitudes of changes in water stable isotopes and estimated surface temperature at EDC compared to DF. Within interglacial periods and during the last glacial inception (Marine Isotope Stages, MIS-5c and MIS-5d), the SMB ratio deviates by up to 30% from what is expected based on differences in water stable isotope records. Moreover, the SMB ratio is constant throughout the late parts of the current and last interglacial periods, despite contrasting isotopic trends. These SMB ratio changes not closely related to isotopic changes are one of the possible causes of the observed gaps between the ice core chronologies at DF and EDC. Such changes in SMB ratio may have been caused by (i) climatic processes related to changes in air mass trajectories and local climate, (ii) glaciological processes associated with relative elevation changes, or (iii) a combination of climatic and glaciological processes, such as the interaction between changes in accumulation and in the position of the domes. Our inferred SMB ratio history has important implications for ice sheet mo